Juno spacecraft demonstrates viability of solar power in deep space

What NASA insisted for decades could not be­a spacecraft using solar energy rather than nuclear power going beyond the orbit of Mars­will be proven false next Monday, July 4th, Independence Day, when the solar-energized Juno space probe arrives at Jupiter.

NASA had maintained that to provide on-board power and heat on spacecraft in deep space, plutonium-powered systems were required­despite the disaster if there were an accident on launch or in a fall back to Earth and the plutonium was released. I broke the story 30 years ago about how the next mission of NASA’s ill-fated Challenger shuttle was to involve lofting a plutonium-powered space probe and I have been reporting in articles, books and on television on the nuclear-in-space issue ever since.

If the Challenger accident did not happen in January 1986 but the shuttle exploded on its next scheduled mission, in May 1986, with the plutonium-powered space probe in its cargo bay, the impacts could have been enormous. Plutonium is the most lethal of all radioactive substances.

Still, when NASA re-scheduled the two plutonium-powered missions it had planned for 1986­one the Galileo mission to Jupiter­it not only publicly declared that plutonium systems to provide on-board power for space probes in deep space were necessary but swore to that in court.

Opponents of the Galileo mission brought suit in U.S. District Court in Washington, D.C. in 1989 seeking to stop the nuclear-energized Galileo shot because of its public health danger in the event of an accident, and they pressed NASA and the U.S. Department of Energy (DOE) on the availability of a safe energy alternative. NASA and DOE officials swore that only nuclear power would do that far out in space, that solar energy could not be harvested beyond the orbit of Mars.

And now comes NASA’s own Juno spacecraft energized by solar energy functioning in deep space. Indeed, NASA acknowledges, “This is the first time in history a spacecraft is using solar power so far out in space.”

Says Bruce Gagnon, coordinator of the Global Network Against Weapons and Nuclear Power in Space: “All during out campaigns to oppose NASA plutonium launches during 1989, 1990 and 1997”­when NASA launched its Cassini space probe with the most plutonium NASA ever used in a power system on a spacecraft­“the space agency maintained in court and in the media that solar would not work as an on-board power source in deep space. Then, in part because of grassroots pressure from around the planet, NASA decided to use solar on the deep space Juno mission.”

“To this day,” Gagnon went on last week, “NASA still maintains that it must use deadly nuclear devices on some of its space missions­further evidence that the nuclear industry maintains a stranglehold on the space agency. The nuclear industry mistakenly views space as a new market for its toxic product that so many have rejected back here on Earth.”

Gagnon added: “We will continue to organize to stop the nuclearization of space­and we will use NASA’s own Juno mission as evidence that the bad seed of nuclear power is not essential for space exploration.”

Juno is not a minor space mission. As NASA states on its Juno mission web page— “The primary scientific goal of the Juno mission is to significantly improve our understanding of the formation, evolution and structure of Jupiter. Concealed beneath a dense cover of clouds, Jupiter, the archetypical ‘Giant Planet,’ safeguards secrets to the fundamental processes underlying the early formation of our solar system. Present theories of the origin and early evolution of our solar system are currently at an impasse. Juno will provide answers to critical science questions about Jupiter, as well as key information that will dramatically enhance present theories about the early formation of our own solar system.”

Juno will, as of Monday, have flown nearly 2 billion miles to reach Jupiter. It was launched from Cape Canaveral, Florida on August 5, 2011. It did a “slingshot maneuver” or “flyby” of Earth in October 2013 to increase its velocity. It has been flying at 60,000 miles per hour. It will orbit Jupiter more than 30 times doing scientific observations.

And although sunlight at Jupiter is just four percent of what it is on Earth, Juno’s solar panels, manufactured by Spectrolab, a division of Boeing, will be able to continue to harvest solar energy. Its passes will include bringing it closer to Jupiter than any mission before.

On its current “Where is Juno?” page, NASA reports: “The Juno spacecraft is in excellent health and is operating nominally.”

The solar energy on 66-foot wide Juno is being generated by three large solar panels. They convert sunlight to electricity at a 28 percent efficiency rate. That’s a little over the 25 percent efficiency rate of the better photovoltaic rooftop panels now being widely used for electric power on Earth. The cost of the mission is $1.1 billion.

Says NASA on its website: “To answer our fundamental questions about origins we especially need to know Jupiter’s internal structure and global water abundance. Juno will map the internal structure by studying its influence on the planet’s gravitational field with unprecedented accuracy. The water abundance will be determined by microwave radiometers that will detect thermal radiation from deep atmospheric layers, a completely new approach. Water ice brought most of the heavy elements to Jupiter. Knowing the water abundance will tell us the original form of that ice and hence help define the conditions and processes in the original cloud of dust and gas that led to the origin of Jupiter. Those same conditions and processes were forming other planets too. Because this enormous planet contains most of the water in the solar system we can expect this investigation to help us understand the origin of the life-giving water on Earth.”

At the end of its mission NASA will send Juno diving into Jupiter and it will burn up.

“NASA going green with solar-powered Jupiter probe,” was the headline of an Associated Press article in USA Today in 2011. “NASA’s upcoming mission to Jupiter can’t get much greener than this: a solar-powered, windmill-shaped spacecraft,” the story began.

But it wasn’t as if solar on Juno was NASA’s first choice. The Associated Press piece described Scott Bolton, the principal investigator for the mission for the Southwest Research Institute, a NASA contractor, as maintaining “the choice of solar was a practical one…No plutonium-powered generators were available to him and his San Antonio-based team…so they opted for solar panels rather than develop a new nuclear source.” The article quoted Bolton as saying: “It’s nice to be green, but it wasn’t because we were afraid of plutonium.”

As bullish as NASA has been in using nuclear power on space probes, once it was as insistent in utilizing atomic energy to power space satellites, too. Then, in 1964, a satellite with a SNAP-9A plutonium system on board failed to achieve orbit and dropped to Earth, disintegrating as it fell, its plutonium fuel dispersing all over the Earth.

Long linking the SNAP-9A accident to an increase in lung cancer on Earth was the late Dr. John Gofman, an M.D. and Ph.D., discover of several radioactive isotopes who did extensive experiments with plutonium for the Manhattan Project, and was associate director of Lawrence Livermore National Laboratory and a professor at the University of California, Berkeley.

With the SNAP-9A accident, NASA switched to using solar energy on satellites. Now all satellites­and the International Space Station­are solar powered.

“A Juno success would be a good sign for future solar-powered missions of all types,” stated the Associated Press “NASA going green with solar-powered Jupiter probe” article.

Unfortunately, if NASA and the DOE have their way, rational energy decision-making won’t necessarily follow a Juno success. “The United States has begun manufacturing nuclear spacecraft fuel for the first time in a generation,” reported SpaceNews last month. SpaceNews saidthe Department of Energy is having its Oak Ridge National Laboratory, Los Alamos National Laboratory and Idaho National Laboratory join together to produce plutonium for NASA space missions. Some plutonium has been produced although “full production of the stuff is still seven years or so away,” it said.

In space as on Earth, solar power works.

But, says Gagnon, “Just like here on Earth there is a tug-of-war going on between those who wish to promote life-giving solar power and those who want nukes. That same battle for nuclear domination is being taken into the heavens by an industry that wants more profit­no matter the consequences. The Global Network will continue to organize around the space nuclear power issue by building a global constituency opposed to the risky and unnecessary nukes in space program.”

With solar-energized Juno’s arrival at Jupiter, this Independence Day should mark a blow for independence from dangerous nuclear power above our heads in space.

Karl Grossman is the professor of journalism at the State University of New York/College at Old Westbury.
Karl is also the author of Cover Up: What You Are Not Supposed to Know About Nuclear Power and other books on nuclear technology, as well as hosting numerous TV programs on the subject including Chernobyl: A Million Casualties, Three Mile Island Revisited and The Push to Revive Nuclear Power.